linux-kernel - [PATCH v11 02/16] KVM: x86: Use a new flag for branch targets

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Message-Id: <20230913124227.12574-3-binbin.wu@linux.intel.com>
Date:   Wed, 13 Sep 2023 20:42:13 +0800
From:   Binbin Wu <binbin.wu@...ux.intel.com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     seanjc@...gle.com, pbonzini@...hat.com, chao.gao@...el.com,
        kai.huang@...el.com, David.Laight@...LAB.COM,
        robert.hu@...ux.intel.com, guang.zeng@...el.com,
        binbin.wu@...ux.intel.com
Subject: [PATCH v11 02/16] KVM: x86: Use a new flag for branch targets

Use the new flag X86EMUL_F_BRANCH instead of X86EMUL_F_FETCH in assign_eip()
to distinguish instruction fetch and branch target computation for features
that handle differently on them, e.g. Linear Address Space Separation (LASS).

As of this patch, X86EMUL_F_BRANCH and X86EMUL_F_FETCH are identical as far
as KVM is concerned.

No functional change intended.

Signed-off-by: Binbin Wu <binbin.wu@...ux.intel.com>
Tested-by: Xuelian Guo <xuelian.guo@...el.com>
---
 arch/x86/kvm/emulate.c     | 5 +++--
 arch/x86/kvm/kvm_emulate.h | 1 +
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 87ee1802166a..274d6e7aa0c1 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -721,7 +721,8 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
 		    (flags & X86EMUL_F_WRITE))
 			goto bad;
 		/* unreadable code segment */
-		if (!(flags & X86EMUL_F_FETCH) && (desc.type & 8) && !(desc.type & 2))
+		if (!(flags & (X86EMUL_F_FETCH | X86EMUL_F_BRANCH)) &&
+		    (desc.type & 8) && !(desc.type & 2))
 			goto bad;
 		lim = desc_limit_scaled(&desc);
 		if (!(desc.type & 8) && (desc.type & 4)) {
@@ -772,7 +773,7 @@ static inline int assign_eip(struct x86_emulate_ctxt *ctxt, ulong dst)
 	if (ctxt->op_bytes != sizeof(unsigned long))
 		addr.ea = dst & ((1UL << (ctxt->op_bytes << 3)) - 1);
 	rc = __linearize(ctxt, addr, &max_size, 1, ctxt->mode, &linear,
-			 X86EMUL_F_FETCH);
+			 X86EMUL_F_BRANCH);
 	if (rc == X86EMUL_CONTINUE)
 		ctxt->_eip = addr.ea;
 	return rc;
diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index e24c8ac7b930..e1fd83908334 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -91,6 +91,7 @@ struct x86_instruction_info {
 /* x86-specific emulation flags */
 #define X86EMUL_F_WRITE			BIT(0)
 #define X86EMUL_F_FETCH			BIT(1)
+#define X86EMUL_F_BRANCH		BIT(2)
 
 struct x86_emulate_ops {
 	void (*vm_bugged)(struct x86_emulate_ctxt *ctxt);
-- 
2.25.1